Adding helpful note about legendCallback (#5094)
Adding helpful note about legendCallback (#5094)

I didn't realize you had to call generateLegend() manually and a quick search tells me that lots of other people have run into this too.
chartjs/Chart.js,nnnick/Chart.js,touletan/Chart.js,chartjs/Chart.js,supernovel/Chart.js,supernovel/Chart.js,touletan/Chart.js,simonbrunel/Chart.js,chartjs/Chart.js,touletan/Chart.js,jtcorbett/Chart.js,touletan/Chart.js,chartjs/Chart.js,jtcorbett/Chart.js,simonbrunel/Chart.js